Novel Ocular Cooling Device for Chronic Ocular Pain

Many patients arrive at our clinics with complaints of eye pain: grittiness, burning, stinging, and stabbing sensations. Often, these patients arrive with a diagnosis of dry eye disease despite having persistent symptoms even with the use of dry eye medications. When lubricants or immunomodulators fail to provide relief for these patients, clinicians should consider a different problem: nerve dysfunction of the ocular surface. When these pain symptoms last more than three months, we call this condition Chronic Ocular Surface Pain (COSP).

Device Concept and Treatment Workflow

In 2021, EyeCool Therapeutics, Inc., was formed to develop an ophthalmic device based on the concept that controlled cooling could modulate lipid-containing tissue. By cooling the lipid-rich myelin sheath that surrounds peripheral nerves of the ocular surface, the ETX-4143 device can transiently disrupt the myelin sheath through a Wallerian-like degenerative process and provide pain relief in patients with COSP.

The EyeCool ETX device contains a proprietary frozen mixture and is stored in the freezer. During treatment, the device is placed on the anesthetized eye. The ETX-4143 device delivers a precise dose of cold thermal energy to the myelinated long ciliary nerves located at the 3-o’clock and 9-o’clock positions posterior to the limbus via two metallic contact surfaces. A transparent silicone speculum holds back the lids and stabilizes the globe to ensure a targeted treatment posterior to the limbus that avoids the cornea, limbal stem cells, and eyelids. This in-office procedure only takes 4 minutes and the entire device is disposable to ensure sterility.

Preclinical Study Findings

The EyeCool ETX device has not yet received approval from the US FDA and is still considered investigational. Because EyeCool acts near the cornea on the ocular nervous system, we evaluated its safety in three preclinical studies. We determined that repeat treatments were safe and found no difference in corneal healing after abrasions were induced in treated and untreated eyes of the same animals.

Human Pilot Study

A double-masked, placebo-controlled study was used to investigate the safety and efficacy of the ETX-4143 device. This pilot study involved 31 participants, 20 of whom received active treatment versus 11 sham. Results showed that ocular pain decreased significantly across all three patient-reported outcomes, and improvement continued throughout the initial 8-week study period. Corneal sensitivity and best corrected visual acuity statistically significantly increased in the treatment group, but not in the sham group. Corneal sensitivity remained improved at one-year post-treatment.

Looking Ahead

Overall, initial findings supported targeted ocular cooling as a promising investigational neuromodulatory approach for chronic ocular surface pain. Our early results support further study, particularly to establish the mechanism of action, magnitude and duration of benefit, retreatment strategy, safety with repeated use, and potential value in dry eye–associated or perioperative settings.

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